Transformation Design & how the flow of rows will be with steps
1) Drag and drop "Get File Names" step from "Input" category.
2) Browse for the folder location where you kept the files & click on "Add" button . Use .* [dot with star] wildcard to get all the files.

4) Preview the step

5)

* Drag & drop "Filter rows" step from "Flow" category & give below condition to get what type of files you want to pick from the folder ( folder may contain different types files. for ex : .txt, .docx , .csv and etc.

* Make hop connection from "Get File Inputs" to "Filter rows"

Condition to fetch txt file (text type files) from the folder (In this example I kept only txt files but there could be another type of files also in the folder)

* Target email in this example is : test4mail4kettle@gmail.com
* If you want to sent to multiple emails use space to add more emails.
* Sender address in this example is : test4mail4kettle@gmail.com* Sender name is : Test Sender